Bisphenol A is produced by reacting excess phenol with acetone in the presence of an acid catalyst. In order to obtain high-purity bisphenol A from this reaction product, low boiling point materials including water are removed therefrom, and crystallization is performed to precipitate a solid adduct crystal of bisphenol A and phenol. After the slurry containing the solid adduct is subjected to solid-liquid separation, phenol is removed from the recovered solid adduct to obtain bisphenol A.
Phenol is produced using cumene as a raw material, and cumene is oxidized using a gas containing oxygen to form cumene hydroperoxide, which is then decomposed under an acidic catalyst to produce phenol and acetone.
FIG. 1 is a simplified schematic diagram illustrating the production process of bisphenol A and the production process of phenol. Referring to FIG. 1, after an oxidization reaction using cumene and oxygen as raw materials is performed, a reaction in which cumene hydroperoxide as a cumene oxide is decomposed is performed. Then, through a purification process, phenol and acetone are produced as a product thereof, and alpha-methylstyrene is additionally produced. Also, bisphenol A is produced by reacting phenol with acetone, and the bisphenol A produced therefrom is concentrated through the removal of low boiling point materials, and then crystallized, washed, and purified to produce bisphenol A.
Regarding such a production process of phenol and a production process of bisphenol A, since the products of the production process of phenol are used as raw materials for a reaction in the production process of bisphenol A, there are typically two processes in a single factory.
Meanwhile, the production process of bisphenol A has a problem in that methanol included as an impurity in acetone which is a raw material acts as a catalyst poison in a reactor, thereby shortening the lifespan of a catalyst. To solve this problem, typically, a distillation tower for removing methanol from the raw material of acetone is separately installed to perform a separation process. However, there is a problem in that the separation between acetone and methanol using distillation requires a large number of stages so that the energy consumption is high.
Also, in the case in which high-purity bisphenol A cannot be obtained due to a large amount of side reaction materials produced, the quality of a bisphenol A product is deteriorated, and in particular, there is a problem in that color at high temperature melting, which is an important factor of a bisphenol A product, cannot be obtained at a desired level.
In relation to this, in order to increase the production amount of bisphenol A, the amount of acetone to be introduced should be increased. However, due to a lowered ratio of phenol to acetone, that is, since the ratio of phenol is relatively lowered, a large amount of side reaction materials are produced. To overcome this problem, the amount of phenol to be introduced is also increased to prevent the relative content reduction of phenol to acetone. However, due to an increase in residence time, the conversion rate of acetone is maintained low.
In the case in which the content of acetone is increased as described above, not only there is a problem in that methanol included as an impurity in acetone acts as a catalyst poison in a reactor, but also a problem in that the amount of unconverted acetone is increased so that a large amount thereof cannot be recovered in a recovery process of acetone through a dehydration column, and therefore, is introduced into a dephenolation process together with water which is a side reaction material of the reaction. The acetone introduced into the dephenolation process may cause a problem of greatly deteriorating a treatment process of wastewater containing phenol, the process included in the dephenolation process operated through extraction.
Therefore, due to a problem caused by acetone, there is a problem in that the production process of bisphenol A is limited by the capacity of a dehydration column provided in the process of recovering acetone.
That is, there is a need for the development of a technology for efficiently removing methanol included in acetone produced in the production process of phenol. There is also a need for the development of a technology capable of, by providing acetone not including methanol for the production process of bisphenol A, improving the lifespan of a catalyst, and at the same time, increasing productivity by improving the selectivity of bisphenol A.